1. Field of the Invention
The present invention generally relates to a fluid monitoring system, and, more particularly, to a new and improved instrument for handling multiple sensors that are used in analyzing blood glucose or other analytes contained therein.
2. Description of the Prior Art
People suffering from various forms of diabetes routinely need to test their blood to determine the level of blood glucose. The results of such tests can be used to determine what, if any, insulin or other medication needs to be administered. In one type of blood glucose testing system, sensors are used to test a sample of blood.
Such a sensor may have a generally flat, rectangular shape with a front or testing end and a rear or contact end. The sensor contains biosensing or reagent material that will react with blood glucose. The testing end of the sensor is adapted to be placed into the fluid being tested, for example, blood that has accumulated on a person's finger after the finger has been pricked. The fluid is drawn into a capillary channel that extends in the sensor from the testing end to the reagent material by capillary action so that a sufficient amount of fluid to be tested is drawn into the sensor. The fluid then chemically reacts with the reagent material in the sensor with the result that an electrical signal indicative of the blood glucose level in the blood being tested is supplied to contact areas located near the rear or contact end of the sensor.
In order to couple the electrical signals produced at the sensor contacts to monitoring equipment, the sensors need to be inserted into sensor holders prior to the sensor end being placed into the fluid being tested. The holders have corresponding mating contact areas that become coupled to the contacts on the sensor when the sensor is inserted into the holder. Consequently, the holders act as an interface between the sensor and monitoring equipment that accumulates and/or analyzes the test results.
Prior to being used, the sensors need to be maintained at an appropriate humidity level so as to insure the integrity of the reagent materials in the sensor. Sensors can be packaged individually in tear-away packages so that they can be maintained at the proper humidity level. For instance, blister type packaging methods could be used. In this connection, the packages can include desiccant material to maintain the proper humidity in the package. In order for a person to use an individual sensor for testing blood glucose, the package must be opened by tearing the seal. Alternatively, some packages require the user to exert force against one side of the package resulting in the sensor bursting or rupturing the foil on the other side. As can be appreciated, the opening of these packages can be difficult. Moreover, once the package is opened, the user needs to be sure that the sensor is not damaged or contaminated as it is being placed into the sensor holder and used to test the blood sample.
U.S. Pat. No. 5,630,986, issued on May 20, 1997, and entitled Dispensing Instrument For Fluid Monitoring Sensors (referred to hereinafter as “the '986 patent”), discloses a type of sensor pack with multiple sensors and a testing blood glucose and dispensing instrument for handling the sensors contained in such a sensor pack. In particular, the sensor dispensing instrument disclosed in the '986 patent is adapted to receive a sensor pack containing a plurality of blood glucose sensors. The sensor pack includes a circular base having a plurality of sensor retaining cavities, each of which hold an individual sensor. Each of the sensors has a generally flat, rectangular shape with a front testing end through which fluid is drawn so as to react with a reagent material in the sensor and an opposite rear, contact end.
The sensor instrument disclosed in the '986 patent includes an outer housing having an upper and a lower case that are pivotable with respect to each other so that the sensor pack can be positioned in the housing on an indexing disk disposed in the housing. With the sensor pack loaded in the housing, a slide latch on a slide actuator disposed on the upper case of the housing controls whether the movement of the slide actuator places the instrument in a display mode or in a testing mode. The instrument is placed into its display mode when the slide latch is moved laterally and the slide actuator is pushed away from its standby position. When in the display mode, a person using the instrument can view data displayed on a display unit in the upper case and/or input data into the instrument.
The instrument is in its testing mode when the slide latch is in its normal position and the slide actuator is pushed towards its testing position. As the slide actuator is moved towards its actuated position, the driver with the knife blade thereon moves toward the testing position of the feed mechanism and the disk drive arm travels in a straight, radially extending groove in the indexing disk such that the disk is not rotated as the feeding mechanism is moving towards its testing position. The knife blade is moved towards one of the sensor cavities in the sensor pack and pierces the foil covering the sensor cavity so as to engage the sensor disposed in the cavity. As the slide actuator and the driver are pushed toward the actuated position of the actuator, the knife blade ejects the sensor out from the sensor cavity and into a testing position near the testing end of the sensor housing.
Once the blood analyzing test is completed, the slide actuator is moved in the opposite direction towards its standby position so that the sensor can be removed from the dispensing instrument. The continued retraction of the driver causes the indexing disk drive arm to travel along a curvilinearly extending groove in the indexing disk, resulting in the rotation of the indexing disk. The rotation of the indexing disk results in the sensor pack being rotated so that the next sensor is positioned in alignment with the knife blade for the next blood glucose test that is to be performed.
Although the sensor instrument disclosed in the '986 patent overcomes many of the problems discussed above in connection with the use of individual sensors, the sensor instrument disclosed in the '986 requires manual force to eject a sensor from the sensor cavity and into a testing position. The user must overcome this force with a thumb slide or a push-pull handle. Some users of have experienced difficulties in the operation and/or manipulation of the disclosed sensor instruments. For example, users with limited dexterity may find the manipulation of the slide latch or the push-pull handle difficult. Similarly, some users, elderly users in particular, may find the operation of these devices complicated or confusing. This may lead to user errors in the manipulation of the slide latch or the push-pull mechanism, which can result in a jam in the operation of the device. Accordingly, it is desirable to have a sensor dispensing instrument utilizing an improved mechanical mechanism that can be more easily manipulated by users with limited dexterity, and is less likely to jam as the result of user error.
In addition, some users have encountered spoiled sensors resulting from partial or incorrect manipulation of the device. This is because a new sensor is moved into alignment with the knife blade at the conclusion of each test. If, for example, a user intending to activate the display mode of the device accidentally moves the slide latch into the testing mode direction, the knife blade may puncture the foil covering the sensor cavity of the new sensor. Even if the user realizes the error and returns the slide latch to the neutral position, the sensor in the punctured sensor cavity will be exposed to the humidity in the air and must be used immediately or discarded. Accordingly, it is desirable to have a sensor dispensing instrument utilizing an improved mechanical mechanism that will eliminate inadvertent spoilage of sensors as the result of user error.